The present invention relates to an antipollution device for collecting fluids escaping from an underwater source, particularly hydrocarbons released through fractures of the water bottom, or from an underwater well, from a sunken ship, or from an underwater pipe.
More particularly, the invention makes possible reduction or even elimination of sea pollution which can result from offshore oil drilling.
The recent blowout from the IXTOC 1 oil well in the Gulf of Mexico revealed the pollution risks involved in offshore drilling operations and illustrated the necessity of using equipment for substantially reducing or eliminating the risks of such pollution until, after the blowout, the well can again be controlled (for example by drilling diverted wells and optionally by cementing).
There has already been proposed antipollution devices for an underwater oil well, comprising an element adapted to cap the wellhead for collecting the hydrocarbons escaping therefrom.
U.S. Pat. No. 3,602,299 discloses an apparatus which can be positioned over an underwater hydrocarbon source to achieve combustion of the released hydrocarbons.
U.S. Pat. No. 3,599,434 teaches enclosing an offshore drilling platform with a skirt supported by a floating ring, so as to contain the hydrocarbons which might otherwise pollute the surrounding water.
Canadian Pat. No. 1 063 367 teaches capping an underwater hydrocarbon source with a dome having a central opening through which liquid hydrocarbons rise to the water surface, and with peripheral openings through which gases can escape upwardly, thereby forming an annulus which confines liquid hydrocarbons, thus facilitating their combustion.
In the publication Offshore, vol. 17, October 1977, No. 11, Tulsa (USA) there is disclosed a device comprising a collector element adapted for capping an underwater apparatus from which hydrocarbons escape.
U.S. Pat. No. 3,745,773 describes a drilling and production platform comprising at its lower part a hydrocarbon collecting element, this element being connected to collecting means at the top of the platform.
French Pat. No. 2,062,092 describes a floating flare comprising a vertical pipe having a permeable wall, this pipe connecting a hydrocarbon collecting element located on the water bottom to the water surface.
U.S. Pat. No. 3,548,605 describes a device for controlling a gas leakage at the level of the water bottom. This device comprises a collector element connected to the water surface by an extensible pipe which is initially folded against the collector element when this element is lowered to the water bottom.
U.S. Pat. No. 3,653,215 describes a system for containing an underwater hydrocarbon leak. This system comprises a collector element having a flexible skirt which can be folded or unfolded from the water surface by means of cables, and which comprises, at its upper part, means for recovering the collected gas and liquid.
It is however, difficult to place and hold these prior art devices in position over a source of fluids escaping under pressure, such as a blown well, due to the turbulences produced by the hydrocarbon jet escaping from the well (i.e., the zone of turbulence above this well) and to the overpressures generated when suddenly capping the blown well.